No, don't grind beans and pour water on them, I'm kidding. That would be silly.

Axioms:
Vampires can't be seen in mirrors.
Vampires can be seen from behind.
Light can be both created and collected to produce energy.
Light which isn't sunlight won't hurt vampires.
Vampires
are relatively low maintainance.
Vampires can be made to wear light-coloured cloaks.

Deductions:
If a vampire stands in front of a mirror, light must be created. From the rear, the vampire can be seen, hence light appears to be behaving normally.
However, looking in the mirror the vampire can not be seen. Therefore the light is somehow being duplicated. This 'free' energy could be used as a source of power.

Explanation:
Suppose we place a light source and a vampire between two facing mirrors. The light produced will bounce between the mirrors many times as if the vampire were not present. In addition, for each bounce the light will reflect off the vampire, generating more light.

The original light source can then be removed. We can rely on the extra generated planar light to sustain the process, negating losses from sub-perfect mirrors. In fact 'modulators': automatically regulated, sloping, partially reflective sheets of glass may be required to avoid too much light combusting the vampire.

The majority of the extra light created will reflect off the vampire out from between the two mirrors. Energy from this source can be collected in perpetuity.

Remember to feed the vampire every now and then; a pinta every few months or so should sustain it.

Psst... [EvilPickels]. We know it'll never work - vampires are far too clever to be exploited like this. But denigrating other people's ideas won't win you any croissants. Have a look at the Centrifugal Bucket Method idea to see what a can of worms you're opening.

Edit: [Amos], I like your idea. You should post it. Loris' physics appears sound as well though - when a ray of light hits a vampire standing infront of a mirror, it must be reflected (else people wouldn't be able to see the vamp) and it must also be transmitted out the other side (else people looking in the mirror wouldn't be able to see what's behind ol' Drac. ) As the bakesperson points out, your main problem is going to be the reactor overheating. I suggest filling the mirror-chamber with smoke to absorb some of the light and dampen the exponential increase in energy. [+]

At first sight this looks workable, but as with all these free energy ideas the laws of thermodynamics prevail. Any Vampire placed between two mirrors will instantaneously transform into a bat. Bats are simply black; no energy can be extracted from them.

No I wasn't trying to down play this idea, for all I care this idea could go on about gnomes and unicorns for all I care I just don't understand how something that would never work could get so many crossaints, and a topic like my global warming movie one could get so many fish! I mean it works, it is workable, and it might actually help people be more aware. Yet only 2 +'s...

And somehow people seem to be explaining the wrong things all over the reverser machine one... I won't drag this whole mess into this thread but still... I don't make none sense it aint.

Peter's on to something here. You can't look that perfect by accident every time. They must be casting a reflection that can only be seen by themselves, other vampires, and likely the occasional gifted human. Therefore no "free energy". I'm tempted to mfd this for bad science. (+).

[UB] I think there would be a net energy gain. However, more worryingly, a perfectly reflective coating all over might inadvertantly protect them from being vapourised by sunlight, thus aloowing vampires to come out in the daylight.
Whilst this may be dangerous for us, I can see a lot of Vampires picking up on this, as it would mean they could get out a lot more.
I heard a Vampire gto killed last week by a famous vampire hunter. Unfortunately, his weapon of choice was a cheap chinese import, which disintegrated as he tried to nail it into his bloodsucking victim. However, he still died. It seems that although the main weapon didn't pierce his heart, some of the smaller pieces which broke off did the job.
Which just proves that too much stake and chips really isn't good for you.

1st of all, vampires don't "make" light, they're undead, not light bulbs. Light bounces off them like anything else. However they may absorb light in such a way that will not allow it to be reflected. Vampires may be using this absorbed energy in some way. It would also explain why they die in sunlght: overload.

"ampires may be using this absorbed energy in some way. It would also explain why they die in sunlght: overload"

What if the idea is changed to one that captures the energy of a vampire dying in the sunlight? Based on the (slight) evidence available, a dying vampire relasese quite a bit of energy in the process. I'm imagining a farm of exploding vampires.

[tgu] Hmm. I think it's a frame of reference thing. If you stand behind the vampire - no, I'm running off too - if you place a camera or assistant behind the vampire, you will see light reflected off them from, say, a torch held in your hand. If you peer round the vampire to look at the mirror, you'll see the torchlight reflected off the mirror. Twice as much light has been reflected back to you as you initially shone out. Now make the torch solar powered (knew there was a use for em somewhere) and voila, perpetual energy source.

Note that I seamlessly manoeuvre you into the position of vampire-illuminating assistant. [+]

This idea might actually tap the energy from Hell, using a vampire as a conduit. Once Hell freezes over it will stop working, but in the interim it would have the benefit of reducing infernal temperatures and improving occupant comfort.

It would seem more probable that the extra photons are generated by the vampire's metabolism (which is in turn fuelled by the blood of the innocent.) This would represent an evolutionary adaptation to stalking prey armed with mirrors.

Because the alternative, physically impossible vampires, is clearly _preposterous_.

well maybe this isn't do fantastic if you suppose the following:
1. the human soul has a mass of approximately 21 grams. No kidding: it was measured scientifically, albeit with a small sample of only a few passers-away, way back in 1906 or so. Oddly, the experiment was never repeated.
2. mass and energy are equivalent, according to the equation e=mc^2. By my calcs thats about 4 * 10^72 gigajoules..
3. perhaps vampires feed not on the blood that they suck but on the "soul energy" of their victims.
If all this is true then maybe we could figure out a way to tap into the energy flow that vampires exploit. Selling your soul starts to look pretty profitable, with energy prices in the range $5-20 per GJ.. just a thought

I think vampires have no reflections or shadows because they are not what they seem. The physical manifestation of a vampire does not correspond to their impression on our senses, which is an hallucination. They don't retransmit light. Then again, if they did, it would explain why they had no shadows. Their clothes are also hallucinatory.

All in all it seems likely vampires are constituted of dark matter. Since calculations have indicated that the stratagems of vampire operation would, in a relatively sort time, turned all creatures into vampires, this matches well with the indication that the overhelming bulk of matter in the universe is dark matter. The most obviously visible members of this tribe are mosquitoes. I doubt anyone has taken the trouble to watch a squashed mosquito reassemble itself to confirm this. The only way to be sure of killing these vicious beasts is a wooden toothpick through the heart.

Just add a beam splitting cube lens on both sides of the whole array. Every time a new light beam is doubled by the vampire, each copy is split in half again by the cube before it gets back to the vampire to redouble back to its former strength. Do this in combination with a diamond reflection path, instead of straight linear back and forth, and you will obtain light equilibrium, with all of the exhaust energy vented out to the side through the beam splitter, to be collected by a generator.

Put the beamsplitter on a little retractable motor, and you can even control the power output, much like the cadmium rods in a nuclear power plant, by splitting a larger or smaller %age of the light. The distance between fully immersed and fully retracted cubes would be on the order of microns, though, since light can get out of control so damn quickly.

It's very confusing the "vampires can't be seen in mirrors" thing. I think the only explanation is that they have the ability to polarise light reflected off them. Then, they would be able to be seen in mirrors if viewed straight on (i.e. they'd be able to see themselves in the mirror, which is why (as [PeterSilly] points out)
they are always so well-presented). However if viewed in a mirror at an angle the vampire would be able to adjust the polarisation of light leaving its body to suppress the reflection in the mirror.

I read an interesting article about squid a couple of weeks ago. Apparently they may be doing exactly this to send steganographised messages to other squid, cunningly concealed within their normal camouflage patterns. (linky)

Since the mythology also includes references to vampires not casting shadows it seems possible that the image of a vampire exists only in the mind of the viewer in a direct referential way and that this reference does not represent the actual function of the optical system thus does not obey typical optical rules. This would be in fitting with their generally hallucinatory nature. If they are a natural phenomenon then, like rainbows, a naturalistic explanation can be found.

I did some calculations on this same idea today, and using a system of 8 mirrors (22.5 degrees each to cut down on energy per square inch of mirror, but not so many mirrors to lose control of the beams), maximally efficient water cooling of perforated glass substrates backing the mirrors, High Reflectance modern coatings that can reflect up to 99.99% of certain wavelengths, and a light source starting the chain reaction specifically made to emit that exact wavelength...

You could get up to about 340 MW per vampire, assuming 6 feet x 2 feet mirrors. Much higher than that, and it would not be possible to cool the mirrors fast enough to stop them from hitting their vitrification point and distorting.

There might be a better substrate than soda lime glass, though, which could be cooled faster without shattering, or better coolants than water. Or better mirror technology. Any of these could up the MW output.

But 340MW is on par with a standard nuclear reactor's output per vampire, without meltdown.

Runaway energy increase is controlled by "control mirrors" similar to a nuclear reactor's control rods - these are partially silvered mirrors inserted gradually into the light path to harvest light from the loop. When the amount harvested = the amount duplicated, runaway energy increase stops. Insert the mirrors further, and you can cool down the system / halt it.

The extreme intensity of the beams harvested would absolutely melt solar panels in moments, but if we use a molten salt reactor tower instead (or several, one per control mirror), like those used in very large solar power plants, we can achieve much higher temperatures and basically harvest the light energy with a conventional steam turbine or similar.

For those suggesting that maybe there is a reflection but only vampires can see it - that does NOT invalidate this idea. It would actually make it even MORE efficient, because that would imply that not only is there a photon going through the vampire (because we can still see what's behind him, so there must be light of some kind making it through that is hitting our retina, even if it isn't the only light) and bouncing off the back (we can still see his back), but also bouncing off the front too (in a wavelength only vampires can see for the last one, which is what they see in the mirror). That's even better increase of light per cycle, not less!

[Smurfs] The first step is to use front silvered metal mirrors. Since vampires don't have to breath you can keep the assembly in an inert atmosphere to avoid corrosion problems.

For your power takeoff, why not use the mirror cooling fluid? Cool them with molten salt, and use that to boil water. This means that you don't need the ultra-high reflectance mirrors, since the inefficency there is your power takeoff.

As far as power modulation, just take create two beam paths, one past the vampire and one not. Use a mirror partially inserted into the beam path to divert some of the light away from the vampire.

It's not just a control mirror. It's also the mean by which you harvest the power. Doesn't do any good to have it going around in a loop forever, and you can't put the salt directly into the path, because it would break it (unlike a partial mirror).

Honestly, the system would already have to be pretty nimble and complex anyway, because the diversion/control mirror would heat up to near melting in something like 2 seconds, hehe. So I think you would need several of them, and dart them in and out, or something like that (hard to cool it in situ without disrupting the optics). A problem arises though in that if you don't continuously cool glass, then it will almost definitely shatter when you suddenly do cool it.

Fused quartz might be an option. Lasts 3+ times longer before melting and I don't think it shatters on cooling (much less thermal expansion than normal glass)

I do like the idea of raising and lowering the vampire as a redundant system!

Forget inert gas - why not just a straight up vacuum? This would also help prevent burning the vampire to death, since I believe that is supposed to be possible. If it's a vacuum, then there is zero convective or conductive heat, and any radiant heat is reflected by the vampire perfectly (the whole point of this topic), so the vamp should stay nice and cool (actually, would the vampire reach absolute zero??? Considering they are cold blooded too... Would also help if so, since they wouldn't squirm, and it is more ethical)

The point is what you're harvesting from the path is heat. Since the mirrors are heating up you just use a less than perfect mirror and pull the heat of that. Thus no need for a redirection to a separate solar collector.

There may be a problem with this approach, however. If the flash point of you average vampire is below the point at which energy can be harvested efficiently, you are going to have to have a concentrator at some point.

I'm not sure we've accepted that vampires are perfect reflectors, so keeping them in a vaccum wouldn't neccesarily keep them cool.

No, if you collect heat from the mirrors, you would get about 1/1000th as much energy as by harvesting the beam, maximum.

Let's say you have a high efficiency mirror, 99.99% reflectance. Only 0.01% of the energy is ending up in mirror heat. If you were to only collect that energy, you'd be throwing away 339.6MW out of 340MW. But yes, you could generate 0.34W just from that.

Let's say you have a low efficiency mirror like you suggest, that has 90% reflectance. In order to stop the mirror from melting (you can only cool glass so fast), you would have to reduce the overall amount of power in the system to 3.4 MW. Then you'd get 10% of that from mirror heat, or 0.34MW. Same exact amount as with mirror heat in the high efficiency mirror system.

The bottom line is, mirror cooling is a hard ceiling. You can only draw a fixed maximum of power from mirrors, due to the really bad cooling properties of any sort of glass, its low melting point, and the fact that your mirrors must remain rigid, or the optics will break. Also the mirrors can only be so large due to the size of a vampire.

Molten salt can go up to ~3 times the vitrification point of glass before it boils, AND the salt doesn't have to keep any precise shape, AND you can have as much of the stuff as you want, AND it can be cooled trivially with just water pipes, with no concern for how quickly you cool.

All of this means that if you divert the light and get your coolant heat from externally located salt, then the limit of the system is mirror efficiency. If you get your heat from mirrors, then the limit of the system is (very low) limit on the robustness of your precision optics.

In the case of modern mirror technology, from my research, it is a difference of about 1000x (exactly proportional to the highest efficiency mirrors available)

Again, I'm skipping glass as the mirror material of choice. Steel mirrors are very simple in an inert atmosphere. Back cooling steel mirrors is trivial.

In addition, you are wrong that taking heat off the mirror forces you to reduce the total energy in the system. The only thing that causes the mirror to heat up is the percentage of energy that it doesn't reflect. That is a 99.99% mirror can reflect 100 times more than a 99% mirror without overheating, because the only heat absorbed is the .01% or 1% respectively. As long as you are removing the percentage the mirror absorbs with the cooling/steam system, the total amount of light in the system doesn't matter.

As a thought exercise to clarify the point above, let's imagine that we had the theoretical ability to manufacture PERFECT mirrors, which did not absorb a single photon hitting them.

If that were the case, then the system could have a light loop of infinitely high power. You could literally choose to shoot out a beam of light (and by reflecting it off a shallow or steep secondary mirror or or through a perfect lens, you could change its size and shape) with ANY POWER you wanted. 300MW, 10,000,000MW. 1.21 Jiggawatts. Aything.

You could then use a very shallow mirror to distribute this energy across as large of an array as you wanted of steam reactors. If you had an entire ocean planet somewhere, you could literally heat the ENTIRE FACE OF THE PLANET on your side into steam in 1/10th of a second from a single vampire, with perfect mirrors. Like... this would be a situation where turning the dial the wrong way could cause the system to get out of control and lead to the Earth where you are hosting the reactor to literally explode from the pressure of boiling rocks. That's the kind of power possible with a harvesting system.

By comparison, if you were to intentionally make the mirrors imperfect, you would still get... 0.34MW.

Steel in the back? fine. Maybe it goes up to like 2MW or something. The heat from the steel is still going to melt and mess up your mirror coating at some point - the point where incoming energy meets your maximum speed of cooling. There is still a linear maximum, versus an arbitrarily high maximum with harvested light.

//As long as you are removing the percentage the mirror absorbs with the cooling/steam system, the total amount of light in the system doesn't matter.//
That's exactly what I'm trying to say. Your method has a linear cap, irrespective of light in the system. The harvesting method has an unbounded potential, ramping up production with more light in the system, which we SHOULD be takign advantage of, because that's the whole benefit of a vampire light for free system, is creating as much free light as you can handle...

Yes, I know what a steel mirror is. When I said messes up your coating, I mean that it would distort the smooth surface, sorry for bad wording.

Let's think about the absolute best steel mirror imaginable.

You are limited by the specific heat of water, which you can't change.

But even if a cooling pipe magically absorbs 100% of heat hitting it, not all heat WILL hit it. In the meantime, heat builds up in the space between the pipes, and can still damage your optics (warp the surface of the steel). Even though you don't care about high reflectance, you still need a closed optical loop, or the vampire won't generate new light anymore. So those surfaces must remain smooth.

The best you can do is have a single atom in between your coolant and your light beam. Setting aside the fact that this would eliminate the physical properties of steel (it is an amalgam, not an element), this mirror would instantly crumble though from erosion due to your coolant flowing past...

But even if you could maintain a single atom thick mirror, about 50% of all heat would travel sideways to neighboring parts of the mirror, not into your coolant. Coolant doesn't attract heat, it just removes it when heat happens to contact it. So now we are playing a coin flipping game as to how much heat will be in any given atom of mirror surface per (unit of time required for iron and carbon atoms in steel to vibrate). Let's say it takes 10 units of heat to cause an atom to detach and "boil" off and away. Well even if only 1 heat unit of light is absorbing during one vibration time, 1/(2^10) = 1 out of every 1024 atoms still boils off every vibration time. Once it's gone, it's gone. This will very quickly boil off your entire mirror at much lower amounts of energy than one might expect. You might have to operate at 1/100,000th or less of the energy required to directly boil an atom thick of steel in order to not have to replace your mirrors every 5 minutes.

And that is in fantasy land. Any kind of realistic mirror where you are drawing power from cooling will need realistic size pipes, water coolant, and very humble temperature caps. Again, maybe 2MW, 5 if you're lucky for a vampire sized mirror.

Reflectance, on the other hand, is already at a level of technology capable of 340MW, and it is entirely reasonable to expect it to get up to at least 99.9999% or so reflectance in the future before hitting practical caps.

//If you need to pull more energy, increase the number of mirrors in the chain.//
Nice try. Your mirrors only reflect 90%. Make a chain of even just 7 of them, and you have already lost half the light you started with in the loop, which means that the system will shut down, because the vampire only duplicates light x2 every cycle. You must maintain higher than 50% of the original amount of light in that cycle in ALL mirrors at all times. So you have a hard cap of about **6** vampire-sized mirrors with steel.

You are always going to have a choke point in the system. Since the melting point of steel is above the operating point of molten salt, the operating temperature of molten salt is going to be your limiter.

In practical terms, the maximum amount of energy you want to pull out is 50% of the energy in the system (+/-2% control energy say), since each time the light passes through the vampire it doubles. Say a given mirror is ~98% efficient. You construct a mirror path such that for each pass through the vampire the light passes through about 35 mirrors, with an alternate path that passes through 33. You direct all the light along the 33 mirror path, until all the mirrors reach the operating temperature of molten salt. You then direct the light through a combination of the two paths, maintaining that temperature in equilibrium.

//You must maintain higher than 50% of the original amount of light in that cycle in ALL mirrors at all times. So you have a hard cap of about **6** vampire-sized mirrors with steel.//

Actually you want to pull out exactly 50% in equilibrium, otherwise you get a runaway reaction and melt your mirrors. As I stated in the anno above, the mostl likely equilibrium point is the molten salt operating temperature. Going to a separate collector isn't going to improve that. I freely admit, the more effecient the mirror, the more you can pull out, because the more surfaces the light can reach in a single loop, but I don't believe a separate concentrator helps.

And for the record, the Tg of fused quartz glass is also higher than the operating temperature of molten salt, so is a viable alternative for mirrors.

Both of us are harvesting 50% of the light, obviously. That is a given. You're doing it by using as many mirrors as necessary to get that much light. I'm doing it with my harvesting partial transmission mirror.

Both of us are still limited in out initial amount of light by how intense of light the FIRST mirror in the chain can handle. If it fails, your system breaks.

With heating, inefficient mirrors, this limit for the first mirror will be much lower than in my reflecting system. I can use ~340MW of light energy hitting my first mirror. You can use ~5MW... 50% of 340 is a lot more than 50% of 5.

I don't understand your salt argument at all... Salt's melting point is irrelevant, because when I have harvested my light beam, I don't have to worry about it completing a loop anymore. So I can go ahead and spread it out (with a shallow mirror) to shine on as large of an amount of salt as I want. It could be a whole football stadium full of salt. YOU can only use a 6'x2' vampire sized mirror, though, because you are using the beam within the loop to heat. The only reason I said molten salt is because they use it in reactors now, apparently / it is cheap and compact. But since you can use as large an area as you want, you could use any material you felt like. Hell, you could have a "solar panel" made out of cardboard with custard pumped through it if you spread the light thinly enough over it.

You do have a point about the relative drop per mirror in my system. But that is soluble by progressively less efficient mirrors start with the four nines mirror and work downwards. As far as the mirror size, you are correct about the primary mirrors (the ones on either side of the vampire), but from there outwards the mirrors can be significantly larger just by making the primaries convex. Regardless you still haven't addressed my concerns about the flamability of the initiating vampire limiting your total energy. (and I believe that this will be a problem even in an inert/vacuum system, as the sufficent heat will break the vampire itself down regardless of true combustion)

My point with the salt is that no matter what you do, you are going to have an upper limit on the heat in the system at some point, be it vampire ingition, mirror temperature, or coolant temperature. Yours is entirely dependent on mirror temperature, where, I suspect, there is a strong negative corelation between the efficiency of the mirror and how high a temperature it can stand. Mine is the coolant temperature in the mirror, but either way there is a limit.

Hm, ok! I admit, with convex primary mirrors, your system would probably work fine.

I do still maintain that a system of 6 mirrors that would have to use perfectly complementary parabolic pairs of mirrors (which are very difficult to grind with optical precision, by the way) would be overly difficult to engineer and keep tuned, compared to 4 mirrors at 45 degrees with another one moving in and out... But it is certainly feasible. There might be other counter advantages in a practical setting, too. Whatever.

Flammability of the vampire? We don't know enough to say one way or the other. In a vacuum, there is no convection or conduction, so the only heating of the vampire is from the light beam. So it comes down to whether the vampire absorbs some energy into its body or not. Since the whole premise of the idea is that vampires have bizarre optical properties, I don't think we can assume the answer to that question. It must be empirically determined with an actual vampire.

In the event that vampires do heat up, that will be a problem, but not a crippling one. There are 2 solutions I can think of now for increasing the limits of the system if so:
1) Start a vampire eugenics program, breeding the absolutely most albino, palest skinned vampires available. Pale organs, etc. also desirable.
2) Surgically insert cooling pipes into the vampire. As long as they aren't made of wood, we should be fine. Cool the vampire then directly, as if he were just another one of the mirrors. This will increase the system limit.

Edit: Also, since the vampire's skin is probably where the magic is happening, we could breed fatter, larger vampires with flabbier, wrinklier skin. Then we could cut the skin and stretch it out in front of the light beam without killing the vampire, with cooling across the entire area, to make the vampire effectively act like 5-6 vampires optically.

Actually, if we can find a way to keep vampire skin alive-ish in a reproducible way... then this is a moot point.

Like, for instance, perhaps the skin only needs one point of connection in order to still be part of the vampire. If so, we could flay the skin almost off, then the vampire would probably re-heal more skin in its normal place, and we could repeat.

Attaching the skin to the vampire with carefully trained (training as in, for example grape vines or bonsais) lengths of vampire blood vessels would allow us to cover even more area.

If you could do that, and attach intense cooling to each bit of skin, then we could run the system at a nice low power, like 5-10MW / m^2 or whatever the vampire skin + cooling can handle, and still make virtually infinite energy with few vampires, because one vampire would be able to cover a huge warehouse-sized light beam, instead of just 6'x2' or whatever. 5MW x 500 vampire surface area equivalents, for instance = 1 terawatt!

If, even better, some method could be discovered for how to keep vampire skin alive on its own, then it would be Game Over. Everybody could just carry around their own little battery packs with 1 square centimeter of vampire skin in an enclosed system with a high efficiency solar cell, and power anything from laptops to cars, to houses with slightly scaled versions, etc. on site.

For safety in home and personal use, instead of a constantly monitored light beam, just do it in pulses. I.e., a strobe light is flashed inside the unit, into a loop that recovers only 45%-49% of the initial light going back into the vampire skin in one direction. The rest powers the strobe light + leftover to the appliance or battery.

That way, it can't ever catastrophically fail, but each strobe would sort of linger for long enough to easily capture more energy out of it in solar panels or whatever to get more than the input.